1195 Formatter for date to have consistent Format

[HenrZu]

Changes and Information

Please briefly list the changes (main added features, changed items, or corrected bugs) made:

• print date object per default in iso format using spdlog

If need be, add additional information and what the reviewer should look out for in particular:

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• Every addressed issue is linked (use the "Closes #ISSUE" keyword below)
• New code adheres to coding guidelines
• No large data files have been added (files should in sum not exceed 100 KB, avoid PDFs, Word docs, etc.)
• Tests are added for new functionality and a local test run was successful (with and without OpenMP)
• Appropriate documentation for new functionality has been added (Doxygen in the code and Markdown files if necessary)
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Checks by code reviewer(s)

• Corresponding issue(s) is/are linked and addressed
• Code is clean of development artifacts (no deactivated or commented code lines, no debugging printouts, etc.)
• Appropriate unit tests have been added, CI passes, code coverage and performance is acceptable (did not decrease)
• No large data files added in the whole history of commits(files should in sum not exceed 100 KB, avoid PDFs, Word docs, etc.)
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[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 3 lines in your changes missing coverage. Please review.

Project coverage is 97.21%. Comparing base (1df315d) to head (1b7d250).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
cpp/models/ode_secirts/parameters_io.h	25.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1198      +/-   ##
==========================================
+ Coverage   97.12%   97.21%   +0.09%     
==========================================
  Files         148      154       +6     
  Lines       13782    14203     +421     
==========================================
+ Hits        13386    13808     +422     
+ Misses        396      395       -1     

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[reneSchm]

Very nice addition, makes the logging of dates a lot easier. Good tests too.

The changes requested are only small details.

In models/ide_secir/parameters_io.h:292-298 there are two more dates only used for a log_warning, could you replace them as well?

[reneSchm]

All change requests are addressed (and comments further improved). Code cov fails due to missed lines, which

• were also not covered prior to this PR,
• and consist of logging related code, which we intentionally do not test in most cases.